JP6129676B2 - VEHICLE ELECTRIC MOTOR CONTROL DEVICE AND ELECTRIC POWER STEERING CONTROL DEVICE - Google Patents

Description

  The present invention relates to a control device for an electric motor for a vehicle, and an electric power steering control device that generates an assist force according to steering by using the electric motor as a drive source.

  Conventionally, in a control device for an electric motor for a vehicle, for example, an electric power steering control device, in order to avoid steering lock by an electric brake in the event of a failure, a phase cutoff switch (phase relay) is provided between the motor drive circuit and the electric motor. ). If a semiconductor relay using a semiconductor element such as a MOSFET is adopted as the phase relay, the product can be reduced in size and improved in reliability. However, since a semiconductor relay has a large withstand voltage restriction, it is necessary to protect against a surge voltage generated by the inductance of the electric motor when the phase is interrupted.

Therefore, for example, in Patent Document 1, the semiconductor relay is turned off when the absolute value of the drive current from the motor drive circuit to the electric motor becomes equal to or less than a predetermined reference value and becomes substantially “0”. By turning off the semiconductor relay in a state where no drive current is flowing to the electric motor, it is possible to suppress the generation of a surge voltage from the electric motor.
Moreover, in patent document 2, after turning off all the semiconductor switch elements which comprise an inverter circuit, the semiconductor relay is turned off after predetermined time progress. In this way, by delaying the timing for turning off the semiconductor relay, it is possible to suppress the application of a large surge voltage generated immediately after the drive current to the electric motor is cut off to the semiconductor relay.

JP 2009-220705 A JP 2011-239489 A

  However, as in Patent Document 1, in order to turn off the semiconductor relay when the absolute value of the drive current of the electric motor is around “0”, it is necessary to detect the drive current or the rotation angle of the electric motor with high accuracy. Moreover, if the OFF delay time of the relay drive circuit is large, there is a possibility that the current increases when the semiconductor relay is actually turned off. This problem can be avoided by using a highly accurate current sensor / rotation angle sensor or configuring a relay drive circuit with a small delay time, but a highly accurate sensor or a high-speed circuit causes an increase in cost.

  Further, as in Patent Document 2, even if the semiconductor relay is turned off after a lapse of a predetermined time after all the semiconductor switch elements of the inverter circuit are turned off, the electric motor is rotated by an external force and is in a power generation mode. The drive current does not necessarily decrease after the predetermined time has elapsed. For this reason, there is a possibility that a large surge voltage is generated. If the surge voltage exceeds the breakdown voltage of the semiconductor relay, there is a risk of failure.

  The present invention has been made in view of the circumstances as described above. The purpose of the present invention is to suppress a failure due to a surge voltage without increasing the cost due to higher accuracy or higher speed while improving reliability. Another object of the present invention is to provide a vehicle electric motor control device and an electric power steering control device.

A control device for an electric motor for a vehicle according to the present invention includes a drive circuit for driving and controlling an electric motor, a drive line between the drive circuit and the electric motor, a semiconductor switch, and a current path of the semiconductor switch A diode connected in parallel to the drive circuit, and a cutoff means for cutting off the energization from the drive circuit to the electric motor, and the cutoff means after a predetermined time corresponding to a delay time of the drive circuit. Predicting the direction or current value of the flowing current and controlling the shut-off means, and shutting off the energization by the shut-off means, when the current flows through the semiconductor switch in the direction along the forward direction of the diode ; and The semiconductor switch is turned off when the current flowing through the current path of the semiconductor switch is in the direction opposite to the direction of the diode and the current value of the current is not more than a predetermined value. That.
An electric power steering control device according to the present invention is an electric power steering control device that generates an assist force according to steering by using an electric motor as a driving source, the driving circuit for driving and controlling the electric motor, and the driving A semiconductor switch disposed on a drive line between the circuit and the electric motor, and a diode connected in parallel to the current path of the semiconductor switch, and energizing the electric motor from the drive circuit A shut-off means for shut-off , predicting a direction or a current value of a current flowing through the shut-off means after a predetermined time corresponding to a delay time of the drive circuit, controlling the shut-off means, and energizing the shut-off means. when blocking, when the current in a direction along the forward direction of the diode in the semiconductor switch is flowing, and the semiconductor switch Current flowing through the flow passage, in the direction opposite to the direction of the diode, and the current value of the current is turned off the semiconductor switch when it is less than the predetermined value, it is characterized.

According to the present invention, when the energization from the drive circuit to the electric motor is interrupted by the interrupting means, the current flowing through the semiconductor switch changes its path toward the diode, so the change in the drive current is small, Generation of a surge voltage from the electric motor can be suppressed. Therefore, it is possible to protect against a surge voltage generated from the electric motor at the time of interruption while improving the reliability by the interruption means having the semiconductor switch. Further, it is not necessary to detect the drive current or the rotation angle of the electric motor with high accuracy, and it is difficult to be influenced by the delay time of the drive circuit.
Accordingly, it is possible to provide a vehicle electric motor control device and an electric power steering control device capable of suppressing a failure due to a surge voltage without increasing costs due to high accuracy or high speed while improving reliability.

It is a schematic block diagram of an electric power steering device. 1 is a circuit diagram showing an electric power steering control device according to a first embodiment of the present invention. It is a flowchart which shows 1st control operation when a failure generate | occur | produces in an electric power steering control apparatus. It is a timing chart which shows the relationship between the drive current of U phase in a electric motor, V phase, and W phase, and the timing which turns off each phase relay. It is a flowchart which shows the 2nd control operation when a failure generate | occur | produces in an electric power steering control apparatus. It is a flowchart which shows the 3rd control operation when a failure generate | occur | produces in an electric power steering control apparatus. It is a flowchart for demonstrating 4th control operation when a failure generate | occur | produces in an electric power steering control apparatus. In FIG. 7, it is a flowchart which shows the control action in case an electric motor is reverse rotation. It is a flowchart for demonstrating 5th control operation when a failure generate | occur | produces in an electric power steering control apparatus. In FIG. 9, it is a flowchart which shows the control action in case an electric motor is reverse rotation. It is a flowchart which shows the 6th control operation when a failure generate | occur | produces in an electric power steering control apparatus. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 2nd Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 3rd Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 4th Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 5th Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 6th Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 7th Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 8th Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 9th Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 10th Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 11th Embodiment of this invention. It is a circuit diagram which shows the electric power steering control apparatus which concerns on the 12th Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
Here, an electric power steering control device will be described as an example of a vehicle electric motor control device.
As shown in FIG. 1, an electric power steering device, so-called EPS (Electric Power Steering) system, includes a steering wheel (handle) 100, a steering torque detection sensor 110, an assist motor 120, a control device 130, and the like. . The steering torque detection sensor 110 and the speed reducer 160 are provided in a steering column 150 that includes the steering shaft 140.

  Then, when the driver of the vehicle performs a steering operation, the steering torque generated in the steering shaft 140 is detected by the steering torque detection sensor 110, and based on the steering torque signal S1, the vehicle speed signal S2, etc., the controller 130 By driving the assist motor 120, a steering assist force is generated from the assist motor 120 according to the traveling state. As a result, when the pinion gear 170 provided at the tip of the steering shaft 140 rotates, the rack shaft 180 moves horizontally to the left and right in the traveling direction, so that the operation of the driver's steering 100 is transmitted to the wheels (tires) 200. Change the direction of the vehicle.

[First Embodiment]
Next, a configuration example of the electric power steering control device according to the first embodiment of the present invention will be described. FIG. 2 shows a specific circuit configuration example of the control device 130 in the EPS system shown in FIG.
The control device 130 includes an inverter circuit 1 that drives an assist motor (three-phase motor in this example) 120, an inverter driver circuit 2 that controls the inverter circuit 1, phase relays 3U, 3V, 3W, a power supply relay 4, a power supply IC5, microcomputer 6, driver 7 for power supply relay 4, drivers 8U, 8V, 8W for phase relays 3U, 3V, 3W, booster circuit 9, current detectors (current detection resistors) 10U, 10V, 10W, and relays The protection Zener diodes ZD1 to ZD4 are included.
Although not shown, the microcomputer 6 is supplied with a steering torque signal S1 and a vehicle speed signal S2. The microcomputer 6 drives the assist motor 120 via the inverter driver circuit 2 and the inverter circuit 1 that function as a drive circuit, and generates a steering assist force according to the running state.

The power supply IC 5 supplies operating power to the microcomputer 6 based on a power supply voltage supplied from a power supply such as a battery via, for example, an ignition switch (not shown). Similarly, power is supplied to the booster circuit 9, and the power supply voltage is boosted to generate a boosted voltage.
Based on control by the microcomputer 6, the driver 7 supplies a control signal having a voltage level boosted by the booster circuit 9 to the power supply relay (semiconductor relay) 4 to perform on / off control. The power relay 4 is composed of an N-channel MOSFET, and supplies operating power from the power source to the inverter circuit 1 through the power line 13. The anode and cathode of a Zener diode ZD4 are connected between the source and gate of the MOSFET.

The inverter circuit 1 has a three-phase bridge circuit configuration including three sets of semiconductor elements that drive the U phase, the V phase, and the W phase of the assist motor 120 for each phase via the drive lines 14U, 14V, and 14W. is there. In this example, each semiconductor element is composed of N-channel MOSFETs 1UH, 1UL, 1VH, 1VL, 1WH, and 1WL.
In the MOSFETs 1UH and 1UL, the drain and the source are connected in series between the power supply line 13 and the ground point, and one end of the drive line 14U is connected to the common connection point. In the MOSFETs 1VH and 1VL, the drain and the source are connected in series between the power supply line 13 and the ground point, and one end of the drive line 14V is connected to the common connection point. Further, the MOSFETs 1WH and 1WL have their drains and sources connected in series between the power supply line 13 and the ground point, and one end of the drive line 14W is connected to a common connection point.

  The inverter driver circuit 2 includes H-side drivers 2UH, 2VH, and 2WH corresponding to MOSFETs 1UH, 1VH, and 1WH, which are upstream drive elements (upper arms) in the inverter circuit 1, and downstream drive elements (lower arms). L-side drivers 2UL, 2VL, 2WL corresponding to the MOSFETs 1UL, 1VL, 1WL are provided. The H-side drivers 2UH, 2VH, 2WH and the L-side drivers 2UL, 2VL, 2WL are supplied with the power supply voltage boosted by the booster circuit 9, and are controlled by the microcomputer 6. The gates of MOSFETs 1UH, 1VH, and 1WH are connected to the output ends of the H-side drivers 2UH, 2VH, and 2WH, respectively, and are controlled to be turned on / off. , 1VL, 1WL are connected to perform on / off control.

  Phase relays 3U, 3V, and 3W are provided between inverter circuit 1 and assisting motor 120, that is, on drive lines 14U, 14V, and 14W, respectively. These phase relays 3U, 3V, and 3W use semiconductor switches, in this example, N-channel MOSFETs, which are turned off in the event of a failure to cut off the energization between the inverter circuit 1 and the assisting motor 120. Also, current detectors 10U, 10V, 10W for detecting the drive current of the assist motor 120 are connected on the drive lines 14U, 14V, 14W between the inverter circuit 1 and the phase relays 3U, 3V, 3W. Yes. The current values detected by these current detectors 10U, 10V, and 10W are amplified by an amplifier (not shown) and then supplied to the microcomputer 6. Furthermore, corresponding to each phase relay 3U, 3V, 3W, a driver 8U, 8V, 8W is provided for each phase. The drivers 8U, 8V, and 8W are supplied with the boosted power supply voltage from the booster circuit 9, and based on the control of the microcomputer 6, supply control signals to the gates of the MOSFETs that function as the phase relays 3U, 3V, and 3W. Are driven (on / off control).

The cathodes and anodes of the Zener diodes ZD1 to ZD3 are connected for each phase between the output ends of the drivers 8U, 8V, and 8W and the drive lines 14U, 14V, and 14W on the assist motor 120 side.
In each MOSFET constituting the inverter circuit 1, the phase relays 3U, 3V, 3W and the power relay 4 in FIG. 2, the diodes D1 to D10 between the drain and the source are parasitic diodes.
Moreover, although the current detectors 10U, 10V, and 10W are provided on the inverter circuit 1 side of the drive lines 14U, 14V, and 14W, they may be provided on the assist motor 120 side of the drive lines 14U, 14V, and 14W. .

  In the configuration as described above, when the ignition switch is turned on, the operation power is supplied from the power supply IC 5 to the microcomputer 6 and the power supply voltage is supplied to the booster circuit 9. The power supply voltage boosted by the booster circuit 9 is supplied to the H side drivers 2UH, 2VH, 2WH, the L side drivers 2UL, 2VL, 2WL and the drivers 7, 8U, 8V, 8W of the inverter driver circuit 2, respectively.

  The microcomputer 6 controls the driver 7 and supplies a control signal to the gates of the MOSFETs constituting the power supply relay 4 for on / off control. Further, for example, a pulse width modulation signal (PWM signal) is output from the microcomputer 6 to the inverter driver circuit 2. The H-side drivers 2UH, 2VH, 2WH and the L-side drivers 2UL, 2VL, 2WL in the inverter driver circuit 2 are respectively connected to the MOSFETs 1UH, 1VH, 1WH, 1UL, in the inverter circuit 1 based on the PWM signal. On / off control is performed by supplying drive signals based on the PWM signal to the gates of 1VL and 1WL, respectively.

Further, the microcomputer 6 controls the drivers 8U, 8V, and 8W, and supplies control signals from these drivers 8U, 8V, and 8W to the gates of the MOSFETs constituting the phase relays 3U, 3V, and 3W, respectively. Control off.
When the assist motor 120 is driven, the MOSFETs constituting the power supply relay 4 are turned on and the MOSFETs constituting the phase relays 3U, 3V, 3W are turned on. Further, by turning on / off each MOSFET 1UH, 1VH, 1WH, 1UL, 1VL, 1WL of the inverter circuit 1, the assist motor 120 is driven in three phases via the drive lines 14U, 14V, 14W. At this time, the duty of the PWM signal is varied based on the steering torque signal S1, the vehicle speed signal S2, and the like, and the output torque of the assist motor 120 is controlled.

  On the other hand, when the microcomputer 6 detects a failure connected to the electric brake, the MOSFET constituting the power relay 4 is turned off to cut off the supply of power, and the drivers 8U, 8V, 8W use the phase relay 3U, The MOSFETs constituting 3V and 3W are turned off to block the current flow from the inverter circuit 1 to the assisting motor 120. For example, when MOSFET 1UL has a short circuit failure, parasitic diode D4, drive line 14V, current detector 10V, phase relay 3V, electric motor M, parasitic diode D7, current detector 10U, drive line 14U, induced voltage of the motor, In addition, since a current flows through the path of the MOSFET 1UL (short), it is necessary to turn off the phase relay (particularly 3 V for this path). As a result, the assist motor 120 is forcibly stopped, and the current path (closed loop) generated by the induced voltage when the assist motor 120 rotates is interrupted to suppress the occurrence of electric braking.

Next, the first to sixth control operations of the phase relay (semiconductor relay) when a failure occurs will be described in detail with reference to the flowcharts of FIGS. The first to third control operations are performed by detecting a current with a current detector, and the fourth to sixth control operations are performed by detecting the rotation angle of the electric motor. In the first embodiment, any one of the first to sixth control operations may be performed.
<First control operation>
The first control operation shown in the flowchart of FIG. 3 is to turn off the respective phase relays 3U, 3V, 3W when the current values detected by the current detectors 10U, 10V, 10W are equal to or less than a predetermined current value. is there.
In step S101, when the microcomputer 6 detects that a failure that should disconnect the inverter circuit 1 and the assist motor 120 has occurred, in step S102, the inverter driver circuit 2 causes the MOSFETs 1UH, 1UL, 1VH, 1VL, 1WH, 1WL (1UH to 1WL) are controlled to be in an off state.

  In the next step S103, it is determined whether or not the state in which the OFF operation of each of the MOSFETs 1UH, 1UL, 1VH, 1VL, 1WH, and 1WL is continued for a time τ has elapsed. If it is determined that the time τ or more has elapsed, the ambient temperature of the phase relays 3U, 3V, 3W is detected, and an allowable current value K1 corresponding to this temperature is derived (step S104). The allowable current value K1 is corrected by correcting the avalanche resistance of the phase relays 3U, 3V, 3W according to the ambient temperature and applied to the phase relays 3U, 3V, 3W in light of the energy stored by the motor inductance. Current value to be obtained. This allowable current value K1 is preferably set to a value with a margin with respect to the current value K2 in which the phase relays 3U, 3V, 3W may be broken. The reason for detecting and correcting the ambient temperature in this way is that if the temperature is high, the tolerance to the surge voltage applied to the phase relays 3U, 3V, 3W is reduced, and the allowable width is narrowed.

  In step S105, it is determined whether or not the U-phase relay 3U has been turned off, and whether or not the U-phase drive current Iu is greater than the allowable current value K1. If the OFF operation has been completed or if the drive current Iu is greater than the allowable current value K1, the process proceeds to step S107, whether the V-phase relay 3V has been turned OFF, and whether the V-phase drive current Iv is greater than the allowable current value K1. Determine whether. If the off operation has not been completed in step S105 and the drive current Iu is equal to or smaller than the allowable current value K1, the U-phase relay 3U is switched off (step S106).

  In step S107, if the V-phase relay 3V has been turned off, or if the drive current Iv is larger than the allowable current value K1, the process proceeds to step S109, whether the W-phase relay 3W has been turned off, and whether the W-phase drive current Iw is It is determined whether or not it is larger than the allowable current value K1. On the other hand, if the V-phase relay 3V has not been turned off and if the drive current Iv is equal to or smaller than the allowable current value K1, the V-phase relay 3V is switched off (step S108).

If it is determined in step S109 that the W-phase relay 3W has been turned off or the drive current Iw is greater than the allowable current value K1, the process proceeds to step S111, and the off-operation has not been completed and the drive current Iw is greater than the allowable current value K1. If it is smaller or equal, the W-phase relay 3W is switched off (step S110).
In step S111, it is determined whether or not all the phase relays have been turned off, and the operations in steps S104 to S110 are repeated until completion.

  In the first control operation described above, when the drive currents Iu, Iv, Iw are less than or equal to a predetermined allowable current value K1 based on the current values detected by the current detectors 10U, 10V, 10W, Turn off 3V and 3W. That is, as shown in FIG. 4, the phase relay 3U is a period of Tu1, Tu2, Tu3,..., The phase relay 3V is a period of Tv1, Tv2, Tv3,..., And the phase relay 3W is Tw1, Tw2, Tw3,. During the period, the assist motor 120 can be turned off without generating an excessive surge voltage that destroys the semiconductor switch (MOSFET in this example) constituting the phase relay.

This is because when the current flowing through the semiconductor switch is flowing in the direction along the forward direction of the parasitic diodes D7 to D9, the current flowing through the semiconductor switch is directed toward the parasitic diodes D7 to D9 even if the semiconductor switch is turned off. This is because the current is changed suddenly and there is no sudden change in current, and the surge voltage due to the counter electromotive force of the assist motor 120 hardly occurs.
Even if the current flowing through the semiconductor switch is in the reverse direction of the parasitic diodes D7 to D9, the semiconductor switch can be turned off if the current value is relatively small. At this time, a relatively small surge voltage is generated by the counter electromotive force of the assist motor 120, but the breakdown can be suppressed by setting the allowable current value K1 in consideration of the margin for the avalanche resistance of the semiconductor switch.

As a specific example, it is assumed that the driving current of the assist motor 120 is 8A or less and the phase relays 3U, 3V, 3W are turned off, and the detection error of the current detectors 10U, 10V, 10W is ± 5A. If so, the phase relays 3U, 3V, and 3W are turned off when the detected current value is 3 A or less.
In the first control operation, the entire period in which the current flowing through the phase relays 3U, 3V, 3W flows in the direction along the forward direction of the parasitic diodes D7 to D9 is defined as the cutoff possible period of the phase relays 3U, 3V, 3W. By doing so, the off period of phase relay 3U, 3V, 3W can be lengthened, and the freedom degree of the timing which turns off can be improved.

In addition, when the current flowing through the phase relays 3U, 3V, 3W flows in the reverse direction of the parasitic diodes D7 to D9 and the current value is below a predetermined value, the phase relays 3U, 3V, 3W are turned off. Further, the off period can be further increased, and the degree of freedom of timing for turning off can be further improved.
Therefore, it is possible to suppress the failure of the semiconductor relay due to the surge voltage generated by the counter electromotive force of the assisting motor 120 at the time of phase interruption while improving the reliability by adopting the semiconductor relay for the phase relays 3U, 3V, 3W. In addition, there is no need to increase the number of parts, and there is no increase in cost due to higher accuracy or higher speed.

The first control operation described above is not limited to the flowchart shown in FIG. 3, and various modifications can be made. For example, if the determination in step S101 is performed for each task with a fixed period, a step of determining whether “a predetermined time has elapsed” may be inserted before step S101. Similarly, a step of determining “has a predetermined time elapsed?” May be inserted after step S103.
Steps S102 and S103 are operations for turning off each MOSFET in the inverter circuit 1, but are not essential.
Further, step S104 is provided to correct the semiconductor relay allowable current and the detected values of the current detectors 10U, 10V, and 10W depending on the ambient temperature. Can also be used.
Furthermore, in steps S105, S107, and S109, the determination is made in the order of the U phase, the V phase, and the W phase.

<Second control operation>
In the second control operation, the phase relays 3U, 3V, 3W are turned off when the allowable current value K1 is equal to or less than a predetermined current value. When the current detector 10U, 10V, 10W does not know the peak of the current, it is judged only by the current phase, and when the zero current or negative current flows, the phase relays 3U, 3V, 3W are turned off. ing.
Further, the rotational speed of the assist motor 120 is determined, and the amount of current change during the off-delay time is taken into account when deriving the allowable current value K1.
The flowchart shown in FIG. 5 differs from the first control operation shown in FIG. 3 in that the rotational speed (Nth [rpm]) of the assisting motor 120 is determined in step S504. Further, when the allowable current value K1 is derived, the amount of current change during the off delay time is taken into consideration.
Since other operations are substantially the same as the first control operation including the modification, detailed description thereof will be omitted.

  Next, the second control operation will be described with a specific example. For example, assume a control device 300 in which the delay time of the drive circuits (inverter circuit 1 and inverter driver circuit 2) of phase relays 3U, 3V, and 3W is 0.1 ms at the maximum. When the generated current of the assist motor 120 by the driver's steering operation can be defined as 30 A or less, the current change amount for 0.1 ms is 3. 4A or less. When the phase relays 3U, 3V, 3W are turned off at 8A or less, for example, if the current detection error is ± 2A, the current detection value is 2.6A (8A-2A-3.4A = 2.6A) or less. Turn off at the point.

However, when the rotation speed of the assist motor 120 is higher than 2000 rpm, the current change amount during the off-delay time is too large, so that the phase relays 3U, 3V, 3W are not turned off. Further, it is necessary to set the rotational speed to a level at which it can be said that “the steering operation is performed at a sufficient speed”.
As described above, when the generated current of the assist motor 120 by the driver's steering operation can be defined, the delay time until turning off is grasped, and the rotation speed of the assist motor 120 is limited accordingly. Thus, the phase relays 3U, 3V, 3W are turned off when the current value is equal to or lower than the predetermined current value. By predicting the delay time based on the rotation speed of the assist motor 120, the phase relays 3U, 3V, 3W can be turned off at a more accurate timing.
Therefore, the semiconductor relay can be prevented from malfunctioning due to the surge voltage generated by the counter electromotive force of the assist motor 120 at the time of phase interruption while adopting the semiconductor relay for the phase relays 3U, 3V, 3W to improve the reliability. In addition, there is no need to increase the number of parts, and there is no increase in cost due to higher accuracy or higher speed.

<Third control operation>
In the third control operation, when the phase relays 3U, 3V, and 3W are turned off, the delay time of the inverter driver circuit 2 and the inverter circuit 1 is considered, the current after this delay time is estimated, and a predetermined current is When the value is less than the value, the phase relay is turned off.
In the flowchart shown in FIG. 6, steps S301 to S304 are the same as steps S101 to S104 in FIG.

  In step S305, it is determined whether the U-phase relay 3U has been turned off. If it has been turned off, the process moves to step S309, and it is determined whether or not the V-phase relay 3V has been turned off. If the U-phase relay 3U has not been turned off, the U-phase current Iu ′ after delay of the relay off-time is calculated from the three-phase current vector of the assist motor 120, the rotational speed (±), and the U-phase current phase in step S306. . In subsequent step S307, it is determined whether or not the calculated U-phase current Iu ′ and the allowable current value K1 satisfy the relationship of “Iu ′ ≦ K1”, and if so, the U-phase relay 3U is switched off. (Step S308). When not satisfy | filling, it moves to step S309 and determines whether the V-phase relay 3V has been turned off.

  If it is determined in step S309 that the V-phase relay 3V has been turned off, the process proceeds to step S313, and it is determined whether or not the W-phase relay 3W has been turned off. If it is determined that the off operation has not been completed, the V-phase current Iv ′ after delay of the relay off time is calculated from the three-phase current vector of the assist motor 120, the rotational speed (±), and the V-phase current phase (step S310). . In subsequent step S311, it is determined whether or not the calculated V-phase current Iv ′ and the allowable current value K1 satisfy the relationship “Iv ′ ≦ K1”, and if so, the V-phase relay 3V is switched off. (Step S312). When not satisfy | filling, it moves to step S313 and determines whether the W-phase relay 3W has been turned off.

If it is determined in step S313 that the W-phase relay 3W has been turned off, the process proceeds to step S317, where it is determined whether all the phase relays have been turned off. If it is determined that the OFF operation has not been completed, the W-phase current Iw ′ after the relay OFF time delay is calculated from the three-phase current vector of the assist motor 120, the rotational speed (±), and the W-phase current phase (step S314). . In subsequent step S315, it is determined whether or not the calculated W-phase current Iw ′ and the allowable current value K1 satisfy the relationship “Iw ′ ≦ K1”, and if so, the W-phase relay 3W is switched off. (Step S316). If not, the process moves to step S317, and it is determined whether all the phase relays have been turned off.
In step S317, it is determined whether or not all the phase relays have been turned off, and the operations in steps S304 to S316 are repeated until completion.

Here, assuming that the rotation speed of the assist motor 120 does not change suddenly due to inertia, the current of each phase can be approximated by a sine wave. The current of each phase after [s] can be estimated by the following equation.
i _X = I × sin (ωt−θ _X )
_X = u, v, w
However,
θ _X : current phase of U phase / V phase / W phase ω: rotational angular velocity (information including rotational direction)
I: The magnitude of the current vector. In the above equation, if the delay time of the phase relay drive circuit is applied to t, when the phase relay is turned off, the current actually flowing at the moment when the phase relay is turned off can be estimated.

Thus, according to the third control operation described above, the phase relay is estimated by estimating the current at the moment when the phase relay is actually turned off, and allowing the turning-off operation when it is estimated that the phase relay is below the specified value. Can be safely turned off.
In addition, the magnitude of the current vector is obtained from the current value flowing through the phase relays 3U, 3V, 3W, and flows through the phase relays 3U, 3V, 3W based on the rotation angle of the assist motor 120, the current vector, and the rotation speed of the motor. By detecting the direction of the current, it is possible to estimate the direction of the current when the phase relays 3U, 3V, 3W are actually turned off, even if a delay occurs until the phase relays 3U, 3V, 3W are actually turned off.
Therefore, the semiconductor relay can be prevented from malfunctioning due to the surge voltage generated by the counter electromotive force of the assist motor 120 at the time of phase interruption while adopting the semiconductor relay for the phase relays 3U, 3V, 3W to improve the reliability. In addition, there is no need to increase the number of parts, and there is no increase in cost due to higher accuracy or higher speed.

As in the first and second control operations, if the determination in step S301 is performed, for example, for each task with a fixed period, a step of determining “whether a predetermined time has passed” before step S301. May be included. Similarly, a step of determining “has a predetermined time elapsed?” May be inserted after step S303.
Steps S302 and S303 are for turning off each MOSFET in the inverter circuit 1, but are not essential.
Further, step S404 is provided for correcting the allowable current of the semiconductor relay and the detection value of the current detector 10 depending on the ambient temperature. However, a fixed value may be used regardless of the ambient temperature. it can.
Furthermore, in steps S305, S309, and S313, the determination is made in the order of the U phase, the V phase, and the W phase, but the determination order of each phase is not limited.

<Fourth control operation>
In the fourth control operation, the phase relay is turned off when the assist motor 120 is in an angle range in which the assist motor 120 can be turned off. That is, if various design parameters of the motor are known, the voltage phase and current phases Qu, Qv, Qw induced in each phase can be estimated by detecting the rotation angle of the assist motor 120. Accordingly, the phase relays 3U, 3V, 3W are turned off.
In the flowchart shown in FIG. 7, steps S201 to S204 are the same as steps S101 to S104 in FIG.
In step S205, it is determined whether the assist motor 120 is rotating forward or backward. In the case of normal rotation, it is determined in step 206 whether or not the U-phase relay 3U has been turned off. If it has been turned off, the process proceeds to step S209, and it is determined whether or not the V-phase relay 3V has been turned off. On the other hand, if not turned off, it is determined in step S207 whether the U-phase current phase estimated from the rotation angle of the assisting motor 120 is “0 deg ≦ θu ≦ Δθ” or “180 deg−Δθ ≦ θu ≦ 360 deg”. If the condition is satisfied, the U-phase relay 3U is switched off (step S208). If the condition is not satisfied, the process proceeds to step S209 to determine whether or not the V-phase relay 3V has been turned off.

  If it is determined in step S209 that the V-phase relay 3V has been turned off, the process proceeds to step S212, and it is determined whether or not the W-phase relay 3W has been turned off. If not turned off, it is determined in step S210 whether or not the V-phase current phase estimated from the rotation angle of the assist motor 120 is “0 deg ≦ θv ≦ Δθ” or “180 deg−Δθ ≦ θv ≦ 360 deg”. If the condition is satisfied, the V-phase relay 3V is switched off (step S211). If the condition is not satisfied, the process proceeds to step S212 to determine whether or not the W-phase relay 3W has been turned off.

If it is determined in step S212 that the W-phase relay has been turned off, the process proceeds to step S215, and it is determined whether or not all the phase relays have been turned off. If not turned off, it is determined in step S213 whether the W-phase current phase estimated from the rotation angle of the assisting motor 120 is “0 deg ≦ θw ≦ Δθ” or “180 deg−Δθ ≦ θw ≦ 360 deg”. If the condition is satisfied, the W-phase relay 3W is switched off (step S214). If the condition is not satisfied, the process proceeds to step S215 to determine whether or not all the phase relays have been turned off. .
Then, the operations in steps S204 to S214 are repeated until all the phase relays are turned off.
In steps S210 and S213, the current phase range correction amount Δθ is set so that the current flowing through the semiconductor switch does not exceed the avalanche resistance of the semiconductor switch even in the direction along the reverse direction of the parasitic diode. This is the correction amount.

  On the other hand, when it is determined in step S205 that the assist motor 120 is not rotating forward, that is, reversely rotating, the process moves to step S216 in FIG. 8 to determine whether or not the U-phase relay 3U has been turned off. . If it has been turned off, the process proceeds to step S219, and it is determined whether the V-phase relay 3V has been turned off. If not turned off, it is determined in step S217 whether or not the U-phase current phase estimated from the rotation angle of the assist motor 120 is “0 deg ≦ θu ≦ 180 deg + Δθ” or “360 deg−Δθ ≦ θu ≦ 360 deg”. If the condition is satisfied, the U-phase relay 3U is switched off (step S208). If the condition is not satisfied, the process proceeds to step S219 to determine whether the V-phase relay 3V has been turned off.

  If it is determined in step S219 that the V-phase relay 3V has been turned off, the process proceeds to step S222, and it is determined whether or not the W-phase relay 3W has been turned off. If not turned off, it is determined in step S220 whether the rotation angle of the assist motor 120 is “0 deg ≦ θv ≦ 180 deg + Δθ” or “360 deg−Δθ ≦ θv ≦ 360 deg”, and the V-phase current estimated from the rotation angle If the phase satisfies the condition, the V-phase relay 3V is switched off (step S221). If the condition is not satisfied, the process proceeds to step S222, and it is determined whether the W-phase relay 3W has been turned off. .

  If it is determined in step S222 that the W-phase relay 3W has been turned off, the process proceeds to step S215 in FIG. 7 to determine whether or not all the phase relays have been turned off. On the other hand, if not turned off, it is determined in step S223 whether the W-phase current phase estimated from the rotation angle of the assisting motor 120 is “0 deg ≦ θw ≦ 180 deg + Δθ” or “360 deg−Δθ ≦ θw ≦ 360 deg”. If the rotation angle satisfies the condition, the W-phase relay 3W is switched off (step S224), and the process moves to step S215 in FIG. 5. If the condition is not satisfied, step S215 in FIG. To determine whether or not all phase relays have been turned off.

  In the fourth control operation described above, an angle range that can be turned off according to the rotation direction of the assist motor 120 is set for each phase, and the current phase of each phase estimated from the rotation angle of the assist motor 120 is within the above range. Since the phase relays 3U, 3V, and 3W are turned off in the case of the above, the control operation can be performed even when the detection values of the current detectors 10U, 10V, and 10W cannot be used or the reliability is low. For example, it is possible to cope with the case where the current detectors 10U, 10V, 10W or their peripheral circuits have failed.

  As a specific example, assuming that the phase relay 3U, 3V, 3W is turned off at 8A or less, the generated current of the assist motor 120 by the driver's steering operation (external force) can be defined as 30A or less. Set as follows. For example, in the U phase, the drive current is 8 A or less at 0 deg to 15 deg or 165 deg to 360 deg in the forward rotation and 0 deg to 195 deg or 345 deg to 360 deg in the reverse rotation, so the U phase relay 3U can be turned off. If the angle detection error is ± 5 deg, the U-phase relay 3U can be turned off when the detected angle value is 0 deg to 10 deg or 170 deg to 360 deg in the forward rotation and 0 deg to 190 deg or 350 deg to 360 deg in the reverse rotation. The same applies to the V-phase relay 3V and the W-phase relay 3W.

According to the second control operation, the rotation angle of the assist motor 120 is detected, and the direction of the current flowing through the phase relays 3U, 3V, 3W is estimated based on the rotation angle of the assist motor 120. The direction of the current can be estimated without knowing the magnitude of the current with the detectors 10U, 10V, and 10W.
Therefore, it is possible to suppress the failure of the semiconductor relay due to the surge voltage generated by the counter electromotive force of the assisting motor 120 at the time of phase interruption while improving the reliability by adopting the semiconductor relay for the phase relays 3U, 3V, 3W. In addition, there is no need to increase the number of parts, and there is no increase in cost due to higher accuracy or higher speed.

As in the case of the first control operation, if the determination in step S201 is performed for each task having a certain period, for example, a step of determining whether “a predetermined time has passed” may be inserted before step S201. good. Similarly, a step of determining whether “a predetermined time has elapsed” may be inserted after step S203.
Steps S202 and S203 are for turning off each MOSFET in the inverter circuit 1, but are not essential.
Further, step S204 is provided to correct the semiconductor relay allowable current and the detection values of the current detectors 10U, 10V, and 10W depending on the ambient temperature. Can also be used.
Furthermore, in steps S206, S209, S212, steps S216, S219, and S222, the determination is made in the order of the U phase, the V phase, and the W phase, but the determination order of each phase is not limited.

The control operations of the flowcharts shown in FIGS. 7 and 8 are also applicable when the generated current of the assist motor 120 due to an external force cannot be defined in consideration of the reaction force from the traveling wheel 200 and the like. In this case, each of the phase relays 3U, 3V, 3W is turned on at the rotational angle of the assist motor 120 in which current flows in the direction along the forward direction of the MOSFET parasitic diodes D7-D9 constituting the phase relays 3U, 3V, 3W. Turn off.
In step S204, “Δθ = 0” is set, and when the current flows in the direction along the reverse direction of the parasitic diode, the off operation is not performed.
As a specific example, the U-phase relay 3U is turned off when the detected angle value is 180 deg to 360 deg in the forward rotation and 0 deg to 180 deg in the reverse rotation. If the angle detection error is ± 5 deg, the U-phase relay 3U is turned off when the angle detection value is 185 deg to 355 deg in the forward rotation and 5 deg to 175 deg in the reverse rotation. The same applies to the V-phase relay 3V and the W-phase relay 3W.

As a result, when the drive current of the assist motor 120 is equal to or less than “0”, that is, when the current flows from the inverter circuit 1 toward the assist motor 120, the phase relays 3U, 3V, 3W are applied when a negative current flows. Will be off. In the state where the current flows in the direction along the forward direction of the parasitic diodes D7 to D9, a large surge voltage is generated because there is no sudden current change even when the MOSFETs constituting the phase relays 3U, 3V, 3W are turned off. Without failure, failure such as destruction can be suppressed.
As described above, semiconductor relays can be prevented from malfunctioning due to a surge voltage generated by the back electromotive force of the assist motor 120 at the time of phase interruption while improving reliability by adopting semiconductor relays in the phase relays 3U, 3V, 3W. . In addition, there is no increase in cost due to an increase in the number of parts, higher accuracy, or higher speed.
In addition, even when the generated current of the assisting motor 120 due to external force cannot be defined, it is possible to prevent failure more reliably.

<Fifth control operation>
In the fifth control operation, when the current phase estimated by the rotation angle of the assisting motor 120 is within a range in which the phase relays 3U, 3V, 3W can be turned off, the off operation is performed. Further, when the rotational speed of the assist motor 120 is determined and the allowable current phase range correction amount Δθ is derived, the angle change amount during the off-delay time is taken into consideration.
In the flowcharts shown in FIGS. 9 and 10, the fourth control is that it is determined in step S604 whether the rotation speed of the assisting motor 120 is equal to or less than Nth [rpm], and the allowable current phase range correction amount Δθ is derived in step S605. It is different from the operation. In deriving the allowable current phase range correction amount Δθ, the phase amount advanced during the OFF delay time by the rotation of Nth [rpm] and the angle detection error are taken into consideration.
Since other operations are substantially the same as the fourth control operation including the modification, detailed description thereof will be omitted.

  Next, the fifth control operation will be described with a specific example. For example, assume a control device 300 in which the delay time of the drive circuits (inverter circuit 1 and inverter driver circuit 2) of phase relays 3U, 3V, and 3W is 1 ms at the maximum. If the rotation speed of the five-pole pair assisting motor 120 is 2000 rpm or less, the current phase change amount for 1 ms is 60 deg or less. For example, in the U phase, the phase relay 3U can be turned off when the motor electrical angle is 240 deg to 300 deg in the forward rotation and 60 deg to 120 deg in the reverse rotation. Therefore, if the angle detection error is ± 5 deg, the phase relay 3U can be turned off when the forward rotation is 245 deg to 295 deg and when the reverse rotation is 65 deg to 115 deg.

Here, similarly to the fourth control operation, the phase relays 3U, 3V, 3W are not turned off when the rotation speed of the assist motor 120 is higher than 2000 rpm.
Even in such a control operation, a semiconductor relay is used for the phase relays 3U, 3V, 3W to improve reliability, and a semiconductor due to a surge voltage generated by the counter electromotive force of the assist motor 120 at the time of phase interruption. Relay failure can be suppressed. In addition, there is no need to increase the number of parts, and there is no increase in cost due to higher accuracy or higher speed.

<Sixth control operation>
In the sixth control operation, the current phase is estimated after the delay time of the phase relay off, and the current flows in the direction along the forward direction of the parasitic diodes D7 to D9 of the MOSFETs constituting the phase relays 3U, 3V, 3W. In this case, the phase relays 3U, 3V, 3W are turned off. If the current value is measured by the current detector 10 and the current peak, rotation angle, rotation direction, and current rotation angle are known, the current value after a predetermined time is determined by the delay time of the inverter circuit 1 and the inverter driver circuit 2. Can be predicted. Therefore, the phase relays 3U, 3V, 3W are turned off according to the predicted current value.
In this case, considering the delay time, the off operation is performed slightly before the actual off timing. However, the prediction is based on the assumption that the rotation speed does not change suddenly due to the inertia of the assist motor 120.

In the flowchart shown in FIG. 11, steps S401 to S404 are the same as steps S101 to S104 in FIG.
If it is determined in step S404 that the U-phase relay 3U has been turned off, the process moves to step S408, and it is determined whether or not the V-phase relay 3V has been turned off. If the U-phase relay 3U has not been turned off, the U-phase current phase θu ′ after the relay-off time delay is calculated from the rotational speed (±) of the assist motor 120 and the current U-phase current phase in step S405. In subsequent step S406, it is determined whether or not the calculated U-phase current phase θu ′ is “180 deg ≦ θu ′ ≦ 360 deg”, and if it is within the range, the U-phase relay 3U is switched off (step S407). If it is out of range, the process proceeds to step S408, and it is determined whether or not the V-phase relay 3V has been turned off.

  If it is determined in step S408 that the V-phase relay 3V has been turned off, the process proceeds to step S412 to determine whether or not the W-phase relay 3W has been turned off. If it is determined that the V-phase relay 3V has not been turned off, the V-phase current phase θv ′ after the delay of the relay-off time is calculated from the rotational speed (±) of the assist motor 120 and the current V-phase current phase ( Step S409). In the subsequent step S410, it is determined whether or not the calculated V-phase current phase θv ′ is “180 deg ≦ θv ′ ≦ 360 deg”, and if it is within the range, the V-phase relay 3V is switched off (step S411). If it is out of range, the process moves to step S412 to determine whether or not the W-phase relay 3W has been turned off.

If it is determined in step S412 that the W-phase relay 3W has been turned off, the process moves to step S416, and it is determined whether all the phase relays have been turned off. If it is determined that the W-phase relay 3W has not been turned off, the W-phase current phase θw ′ after the relay-off time delay is calculated from the rotational speed (±) of the assist motor 120 and the current W-phase current phase ( Step S413). In subsequent step S414, it is determined whether or not the calculated W-phase current phase θw ′ is “180 deg ≦ θw ′ ≦ 360 deg”. If within the range, the W-phase relay 3W is switched off (step S415). If it is out of the range, the process moves to step S416, and it is determined whether or not all the phase relays have been turned off.
In step S416, it is determined whether or not all phase relays have been turned off, and the operations in steps S404 to S415 are repeated until completion.

As described above, when only the current phase is used and the current at the moment when the phase relay is actually turned off is estimated to be equal to or less than the specified value, the off operation is permitted. At this time, more reliable control is possible by taking into account variations in the delay time of each product.
Therefore, the semiconductor relay can be prevented from malfunctioning due to the surge voltage generated by the counter electromotive force of the assist motor 120 at the time of phase interruption while adopting the semiconductor relay for the phase relays 3U, 3V, 3W to improve the reliability. In addition, there is no need to increase the number of parts, and there is no increase in cost due to higher accuracy or higher speed.

As in the first to third control operations, if the determination in step S401 is performed for each task having a fixed period, for example, a step of determining “whether a predetermined time has elapsed” is performed before step S401. May be put in. Similarly, a step of determining “has a predetermined time elapsed?” May be inserted after step S403.
Steps S402 and S403 are for turning off each MOSFET in the inverter circuit 1, but are not essential.
Further, step S404 is provided to correct the semiconductor relay allowable current and the detection values of the current detectors 10U, 10V, and 10W depending on the ambient temperature. Can also be used.
Furthermore, in steps S404, S408, and S412, the determination is made in the order of the U phase, the V phase, and the W phase, but the determination order of each phase is not limited.

[Second Embodiment]
In the second embodiment shown in FIG. 12, the source and drain of the N-channel MOSFETs constituting the phase relays 3U, 3V, and 3W are reversely arranged in the first embodiment, and the inverter circuit 1 starts the assist motor. Parasitic diodes D7 to D9 are arranged in the forward direction toward 120. Along with this change in arrangement, the cathodes and anodes of the Zener diodes ZD1 to ZD3 are arranged for each phase between the output terminals of the drivers 8U, 8V and 8W and the drive lines 14U, 14V and 14W on the inverter circuit 1 side. Connected.
Since other basic circuit configurations are the same as those in FIG. 2, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
Even such a configuration is basically the same as that of the first embodiment, and by applying any one of the first to sixth control operations described above, Substantially the same effect can be obtained. Moreover, the current detectors 10U, 10V, 10W are arranged on the drive lines 14U, 14V, 14W, and flow through the phase relays 3U, 3V, 3W based on the current values detected by these current detectors 10U, 10V, 10W. Since the direction of the current is directly detected, the detection accuracy of the direction in which the current flows can be increased.
FIG. 12 shows an example in which the current detectors 10U, 10V, and 10W are provided on the inverter circuit 1 side of the drive lines 14U, 14V, and 14W, as in FIG. 2, but the drive lines 14U, 14V, and 14W are shown. It may be provided on the assist motor 120 side.

[Third Embodiment]
A third embodiment shown in FIG. 13 is obtained by adding phase relays 15U, 15V, 15W, Zener diodes ZD5-ZD7, and drivers 16U, 16V, 16W to the first embodiment described above. Phase relays 15U, 15V, and 15W are arranged in series with phase relays 3U, 3V, and 3W on drive lines 14U, 14V, and 14W, respectively. The phase relays 15U, 15V, and 15W are composed of N-channel MOSFETs, and parasitic diodes D11 to D13 are arranged in the forward direction from the inverter circuit 1 toward the assist motor 120. These phase relays 15U, 15V, and 15W are controlled by drivers 16U, 16V, and 16W. The drivers 16U, 16V, and 16W are supplied with the boosted power supply voltage from the booster circuit 9, and supply control signals to the gates of the MOSFETs that function as the phase relays 15U, 15V, and 15W based on the control of the microcomputer 6. Drive individually (on / off control). Further, the cathodes and anodes of the Zener diodes ZD5 to ZD7 are connected for each phase between the output terminals of the drivers 16U, 16V, and 16W and the drive lines 14U, 14V, and 14W on the phase relays 3U, 3V, and 3W side. doing.
Since other basic circuit configurations are the same as those in FIGS. 2 and 12, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

Even such a configuration is basically the same as in the first and second embodiments, and the same operational effects can be obtained by applying any one of the first to sixth control operations described above. Is obtained. Moreover, the current detectors 10U, 10V, 10W are arranged on the drive lines 14U, 14V, 14W, and flow through the phase relays 3U, 3V, 3W based on the current values detected by these current detectors 10U, 10V, 10W. Since the direction of the current is directly detected, the detection accuracy of the direction in which the current flows can be increased.
Although FIG. 13 shows an example in which the current detectors 10U, 10V, and 10W are provided on the inverter circuit 1 side of the drive lines 14U, 14V, and 14W, the assist motor 120 side of the drive lines 14U, 14V, and 14W is shown. May be provided.

[Fourth Embodiment]
The fourth embodiment shown in FIG. 14 is obtained by removing the phase relays 3W and 15W, the drivers 8W and 16W, and the Zener diodes ZD3 and ZD7 in the third embodiment described above. By arranging two phase relays 3U, 15U and 3V, 15V on the drive lines 14U, 14V in series with the energizing directions of the parasitic diodes D7, D11, D8, D12 reversed, respectively, the drive line is turned off at the time of phase interruption. It is possible to prevent positive and negative currents from flowing through 14U and 14V. Therefore, in the three-phase drive, the configuration of the closed loop circuit can be suppressed by blocking the two phases.

Since other basic circuit configurations are the same as those in FIG. 13, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
Even in such a configuration, basically, by applying any one of the first to sixth control operations, substantially the same effect as the first to third embodiments can be obtained. . Moreover, the current detectors 10U, 10V, 10W are arranged on the drive lines 14U, 14V, 14W, and flow through the phase relays 3U, 3V, 3W based on the current values detected by these current detectors 10U, 10V, 10W. Since the direction of the current is directly detected, the detection accuracy of the direction in which the current flows can be increased.

In FIG. 14, the W-phase relays 3W and 15W, the drivers 8W and 16W, and the Zener diodes ZD3 and ZD7 are removed. However, the U-phase and V-phase relays, drivers and Zener diodes may be removed. .
The phase relays 3U and 3V are disposed on the inverter circuit 1 side, and the phase relays 15U and 15V are disposed on the assist motor 120 side. However, the phase relays 15U and 15V are disposed on the inverter circuit 1 side, and the phase relays 3U and 3V are disposed on the assist motor 120 side. Even if it is arranged on the side, substantially the same effect can be obtained.

[Fifth Embodiment]
In the fifth embodiment shown in FIG. 15, a current detector 10 that detects the drive current of the assist motor 120 is connected between the sources of the MOSFETs 1UL, 1VL, and 1WL and the ground point. The current value detected by the current detector 10 is amplified by an amplifier (not shown) and then supplied to the microcomputer 6.
Since other basic circuit configurations are the same as those in FIG. 2, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
In such a configuration, the above-described fourth to sixth control operations are preferable. By applying these control operations, substantially the same operational effects as those of the first to fourth embodiments can be obtained.

[Sixth Embodiment]
In the sixth embodiment shown in FIG. 16, the source and drain of N-channel MOSFETs constituting the phase relays 3U, 3V, and 3W are arranged in reverse in the fifth embodiment described above, and the inverter circuit 1 is used for assisting. Parasitic diodes D7 to D9 are arranged in the forward direction toward the motor 120. Along with this change in arrangement, the cathodes and anodes of the Zener diodes ZD1 to ZD3 are arranged for each phase between the output terminals of the drivers 8U, 8V and 8W and the drive lines 14U, 14V and 14W on the inverter circuit 1 side. Connected.
Since other basic circuit configurations are the same as those in FIG. 15, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
Even such a configuration is basically the same as that of the fifth embodiment, and similar effects can be obtained by applying the above-described fourth to sixth control operations.

[Seventh Embodiment]
The seventh embodiment shown in FIG. 17 is obtained by changing the current detection position in the fifth embodiment described above, and the current detectors 10a, 10b, and 10c are connected to the L side of each phase in the inverter circuit 1. The MOSFETs 1UL, 1VL, 1WL are provided between the ground point.
Since other basic circuit configurations are the same as those in FIG. 15, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
Even such a configuration is basically the same as that of the fifth embodiment, and similar effects can be obtained by applying the above-described fourth to sixth control operations.
Moreover, in the seventh embodiment, if the fourth control operation is applied, even if a ground fault occurs on the ground detector side of the current detectors 10a, 10b, 10c in the inverter circuit 1, the phase relays 3U, Since the direction of the current flowing through 3V and 3W can be detected, the phase relays 3U, 3V and 3W can be reliably turned off.

[Eighth Embodiment]
In the eighth embodiment shown in FIG. 18, the source and drain of the N-channel MOSFETs constituting the phase relays 3U, 3V, and 3W are reversed in the seventh embodiment, as in the sixth embodiment. The parasitic diodes D7 to D9 are arranged in the forward direction from the inverter circuit 1 toward the assisting motor 120. Along with this change in arrangement, the cathodes and anodes of the Zener diodes ZD1 to ZD3 are arranged for each phase between the output terminals of the drivers 8U, 8V and 8W and the drive lines 14U, 14V and 14W on the inverter circuit 1 side. Connected.
Since other basic circuit configurations are the same as those in FIG. 12, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
Even such a configuration is basically the same as that of the seventh embodiment, and similar effects can be obtained by applying the fourth to sixth control operations described above.
In addition, in the eighth embodiment, if the fourth control operation is applied, even if a ground fault occurs on the grounding point side of the current detectors 10a, 10b, 10c in the inverter circuit 1, the phase relays 3U, Since the direction of the current flowing through 3V and 3W can be detected, the phase relays 3U, 3V and 3W can be reliably turned off.

[Ninth Embodiment]
The ninth embodiment shown in FIG. 19 is obtained by adding phase relays 15U, 15V, 15W, Zener diodes ZD5-ZD7, and drivers 16U, 16V, 16W to the above-described eighth embodiment. Phase relays 15U, 15V, and 15W are arranged in series with phase relays 3U, 3V, and 3W on drive lines 14U, 14V, and 14W, respectively. The phase relays 15U, 15V, and 15W are composed of N-channel MOSFETs, and parasitic diodes D11 to D13 are arranged in the forward direction from the inverter circuit 1 toward the assist motor 120. These phase relays 15U, 15V, and 15W are controlled by drivers 16U, 16V, and 16W. The drivers 16U, 16V, and 16W are supplied with the boosted power supply voltage from the booster circuit 9, and supply control signals to the gates of the MOSFETs that function as the phase relays 15U, 15V, and 15W based on the control of the microcomputer 6. Drive individually (on / off control). Further, the cathodes and anodes of the Zener diodes ZD5 to ZD7 are connected for each phase between the output terminals of the drivers 16U, 16V, and 16W and the drive lines 14U, 14V, and 14W on the phase relays 3U, 3V, and 3W side. doing.

Since other basic circuit configurations are the same as those in FIG. 15, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
Even such a configuration is basically the same as that of the seventh embodiment, and similar effects can be obtained by applying the fourth to sixth control operations described above.
In FIG. 19, the phase relays 3U, 3V, 3W are arranged on the inverter circuit 1 side, and the phase relays 15U, 15V, 15W are arranged on the assisting motor 120 side, but the phase relays 15U, 15V, 15W are arranged on the inverter circuit 1 side. Even if the phase relays 3U, 3V, 3W are arranged on the assisting motor 120 side, substantially the same effect can be obtained.

[Tenth embodiment]
The tenth embodiment shown in FIG. 20 is obtained by removing the phase relays 3W and 15W, the drivers 8W and 16W, and the Zener diodes ZD3 and ZD7 in the ninth embodiment described above. By arranging the two phase relays 3U, 15U and 3V, 15V on the drive lines 14U, 14V in series with the energizing directions of the parasitic diodes D7, D11, D8, D12 reversed, respectively, when the phase relay is shut off, It is possible to prevent positive and negative currents from flowing through the drive lines 14U and 14V. Therefore, in the three-phase drive, the configuration of the closed loop circuit can be suppressed by blocking the two phases.

Since other basic circuit configurations are the same as those in FIG. 19, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
Even in such a configuration, substantially the same operational effects can be obtained by basically applying the fourth to sixth control operations.
In FIG. 20, the W-phase relays 3W and 15W, the drivers 8W and 16W, and the Zener diodes ZD3 and ZD7 are removed. However, the U-phase or V-phase relays, drivers and Zener diodes may be removed. .
The phase relays 3U and 3V are disposed on the inverter circuit 1 side, and the phase relays 15U and 15V are disposed on the assist motor 120 side. However, the phase relays 15U and 15V are disposed on the inverter circuit 1 side, and the phase relays 3U and 3V are disposed on the assist motor 120 side. Even if it is arranged on the side, substantially the same effect can be obtained.

[Eleventh embodiment]
The eleventh embodiment shown in FIG. 21 is obtained by changing the current detection position in the ninth embodiment, and the current detectors 10a, 10b, and 10c are connected to the L side of each phase in the inverter circuit 1. The MOSFETs 1UL, 1VL, 1WL are provided between the ground point.
Since the other basic circuit configuration is the same as that of FIG.
Even such a configuration is basically the same as that of the ninth embodiment, and substantially the same operational effects can be obtained by applying the fourth to sixth control operations.

Moreover, in the eleventh embodiment, if the fourth control operation is applied, even if a ground fault occurs on the ground detector side of the current detectors 10a, 10b, 10c in the inverter circuit 1, the phase relays 3U, Since the direction of the current flowing through 3V and 3W can be detected, the phase relays 3U, 3V and 3W can be reliably turned off.
In FIG. 21, the phase relays 3U, 3V, 3W are arranged on the inverter circuit 1 side and the phase relays 15U, 15V, 15W are arranged on the assisting motor 120 side in the same manner as FIG. 19, but the phase relays 15U, 15V, 15W are arranged. Even if the inverter circuit 1 side and the phase relays 3U, 3V, 3W are arranged on the assist motor 120 side, substantially the same operation and effect can be obtained.

[Twelfth embodiment]
The twelfth embodiment shown in FIG. 22 is obtained by removing the phase relays 3W and 15W, the drivers 8W and 16W, and the Zener diodes ZD3 and ZD7 in the eleventh embodiment. By arranging the two phase relays 3U, 15U and 3V, 15V on the drive lines 14U, 14V in series with the energizing directions of the parasitic diodes D7, D11, D8, D12 reversed, respectively, when the phase relay is shut off, It is possible to prevent positive and negative currents from flowing through the drive lines 14U and 14V. Therefore, in the three-phase drive, the configuration of the closed loop circuit can be suppressed by blocking the two phases.

Since other basic circuit configurations are the same as those in FIG. 21, the same reference numerals are given to the same components, and detailed descriptions thereof are omitted.
Even such a configuration is basically the same as that of the eleventh embodiment, and the same effect can be obtained by applying the fourth to sixth control operations.
In addition, in the twelfth embodiment, if the fourth control operation is applied, even if a ground fault occurs on the grounding point side of the current detectors 10a, 10b, 10c in the inverter circuit 1, the phase relays 3U, Since the direction of the current flowing through 3V and 3W can be detected, the phase relays 3U, 3V and 3W can be reliably turned off.

In FIG. 22, the W-phase relays 3W and 15W, the drivers 8W and 16W, and the Zener diodes ZD3 and ZD7 are removed. However, the U-phase or V-phase relays, drivers and Zener diodes may be removed. .
The phase relays 3U and 3V are disposed on the inverter circuit 1 side, and the phase relays 15U and 15V are disposed on the assist motor 120 side. However, the phase relays 15U and 15V are disposed on the inverter circuit 1 side, and the phase relays 3U and 3V are disposed on the assist motor 120 side. Even if it is arranged on the side, substantially the same effect can be obtained.

According to the configuration as in the first to twelfth embodiments and the first to sixth control operations, the degree of freedom of timing at which the phase relay can be turned off is increased, so that the current detection accuracy may be low. In addition, since the energization direction can be determined by the rotation angle and the rotation direction of the electric motor, the determination can be easily made only by the angle detection value without using the current value. This angle detection value may also have low accuracy.
In addition, since there is no problem even if the timing of turning off the phase relay is shifted, there is no problem even if the responsiveness of the drive circuit (inverter circuit 1 and inverter driver circuit 2) is poor.
Furthermore, since it is not the structure which absorbs a surge voltage with hardware, the cost rise by the increase in a number of parts can also be suppressed.

Therefore, when detecting a failure connected to the electric brake and turning off the phase relay, the surge generated from the inductance of the electric motor accompanying the turning off of the phase relay is suppressed from being applied beyond the avalanche withstand voltage of the semiconductor switch. it can.
Therefore, semiconductor relays are used for phase relays to reduce size and improve reliability, and to prevent failure of semiconductor relays due to surge voltage generated by the back electromotive force of the electric motor when the phase relay is turned off. It can be realized without incurring up.

  In each of the above-described embodiments, in addition to the example in which a current detector is provided and the current value is used, an example in which control is performed using the detected angle value of the electric motor without using the current detector has been described. That is, since the operation of the inverter circuit 1 is stopped at the time of failure, the direction in which the phase current flows depends on the power generation of the electric motor. Therefore, it is also possible to control using the detected angle value of the electric motor without using the current value.

Further, an example has been described in which each phase relay 3U, 3V, 3W is an N-channel MOSFET, and each MOSFET is turned off when a current flows through the MOSFET in a direction along the forward direction of the parasitic diodes D7 to D9. However, each phase relay 3U, 3V, 3W can be applied to various configurations as long as it is a semiconductor relay having a semiconductor switch and a diode (including a parasitic diode) connected in parallel with the current path of this semiconductor switch. is there.
For example, the present invention can also be applied to a configuration in which a bipolar transistor (or IGBT) and a diode are connected in parallel between the collector and emitter of this bipolar transistor. Then, the bipolar transistor may be turned off when a current flows in a direction along the forward direction of the diode. Alternatively, the bipolar transistor may be turned off when the current flowing in the reverse direction of the diode in the bipolar transistor is equal to or less than a predetermined value.
Furthermore, the electric power steering control device has been described as an example of the control device for the vehicle electric motor. However, the electric power steering control device is applicable to other devices and systems as long as the vehicle electric motor requires a phase relay. .

Here, technical ideas that can be grasped from the above embodiments will be described together with the effects thereof.
In one aspect of the control apparatus for an electric motor for a vehicle, the magnitude of a current vector is obtained from a current value flowing through the cutoff means, and the cutoff means is based on a rotation angle, a current vector, and a rotation speed of the electric motor. The control apparatus of the electric motor for vehicles which detects the direction of the electric current which flows through.
According to the above configuration, even when a delay occurs between the turning-off operation of the shut-off means and the actual turning-off, the direction of the current when actually turning off can be estimated.

In a preferred aspect of the control apparatus for an electric motor for a vehicle, a current detection means for detecting a drive current of the electric motor is further provided on the drive line, and the blocking means is based on a current value detected by the current detection means. The control apparatus of the electric motor for vehicles which detects the direction of the electric current which flows into.
According to the above configuration, since the current value on the drive line can be detected directly, the detection accuracy in the direction in which the current flows can be increased.

  M ... Electric motor, 1 ... Inverter circuit, 2 ... Inverter driver circuit, 3U, 3V, 3W, 15U, 15V, 15W ... Phase relay, D7-D9, D11-D13 ... Parasitic diode, 8U, 8V, 8W, 16U , 16V, 16W ... driver 10, 10a, 10b, 10c, 10U, 10V, 10W ... current detector, 14U, 14V, 14W ... drive line, 100 ... steering wheel, 200 ... wheel, 300 ... control device

Claims (3)

A drive circuit for driving and controlling the electric motor;
The semiconductor device is disposed on a drive line between the drive circuit and the electric motor, and includes a semiconductor switch and a diode connected in parallel to the current path of the semiconductor switch, from the drive circuit to the electric motor. And means for shutting off the energization of the
In the case where the current direction or the current value flowing through the interrupting means after a predetermined time corresponding to the delay time of the drive circuit is predicted to control the interrupting means, and the energization is interrupted by the interrupting means, the semiconductor switch When a current flows in a direction along the forward direction of the diode , and when a current flowing through the current path of the semiconductor switch is in a direction opposite to the direction of the diode and the current value of the current is equal to or less than a predetermined value To turn off the semiconductor switch,
A control device for an electric motor for a vehicle. The control apparatus for an electric motor for a vehicle according to claim 1 , wherein a rotation angle of the electric motor is detected, and a direction of a current flowing through the blocking means is detected based on the rotation angle of the electric motor. An electric power steering control device that generates an assist force according to steering by using an electric motor as a drive source,
A drive circuit for driving and controlling the electric motor;
The semiconductor device is disposed on a drive line between the drive circuit and the electric motor, and includes a semiconductor switch and a diode connected in parallel to the current path of the semiconductor switch, from the drive circuit to the electric motor. And means for shutting off the energization of the
In the case where the current direction or the current value flowing through the interrupting means after a predetermined time corresponding to the delay time of the drive circuit is predicted to control the interrupting means, and the energization is interrupted by the interrupting means, the semiconductor switch When a current flows in a direction along the forward direction of the diode , and when a current flowing through the current path of the semiconductor switch is in a direction opposite to the direction of the diode and the current value of the current is equal to or less than a predetermined value To turn off the semiconductor switch,
An electric power steering control device.